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Chapter 1 Introduction to Information Technology 17
Internet
The Internet is a worldwide communication network that connects
individual computer networks. Messages are exchanged between these
networks, and then the destination network must deliver the message
to the correct computer in its network. It sounds complicated, but the
process is very simple to understand.
The routing mechanism is based on small fi le fragments called fi
packets. The transmission control protocol (TCP) identifies a file fi to be fi
sent and breaks it into packets, each of which is given a header. The
packet header contains the:
• file’s source computer’s fi Internet protocol (IP) address, which
uniquely identifies each computer on a network; fi
• destination computer’s IP address;
• packet number; and
• total number of packets in the entire file. fi
These packets are sent though the network of networked computers,
possibly not on the same path, as shown in Figure 1-12.
World Wide Web
The World Wide Web (WWW) is a subset of the Internet that consists of
a collection of documents connected by uniform resource locator (URL)
codes and hypertext protocol, as illustrated in Figure 1-13.
Computer A
Packet
Switch
Packet
Switch
Packet
Switch
Computer B
Computer C
Computer D
Packet
Switch
Packet
Switch
Packet
Switch
Packet
Switch
To C
T
o
C
To
C
T
o C
T
o
D
To
D
To D
To D
To D
To D
To C
Goodheart-Willcox Publisher; Macrovector/Shutterstock.com
Figure 1-12. The TCP breaks a file into packets, which are then sent through the network.